Maria Miller will promise to 'fight the corner' for the arts in the coming spending review. Photograph: Peter Macdiarmid/Getty Images

British culture should be presented as a "commodity" and "compelling product" to sell at home and abroad, the culture secretary, Maria Miller, will argue in her first speech on the arts since taking up the job in September.

Speaking to an audience of senior cultural figures at the British Museum, she will pledge to "fight the corner" for the arts as hard as possible with the Treasury in the runup to the coming spending review.

But, she said, the argument for continued arts funding must be made primarily on economic grounds so that it "will get traction, not in the press, but with my colleagues – and with the country at large".

She will say: "In an age of austerity, when times are tough and money is tight, our focus must be on culture's economic impact … We must demonstrate the healthy dividends that our investment [in the arts] continues to pay."

She will argue that the contribution of the arts goes beyond direct economic impact, but helps create what amounts to a brand identity of Britain overseas, with British arts helping to market exports.

"I would argue that culture should be seen as the standard bearer for our efforts to engage in cultural diplomacy, to develop soft power, and to compete, as a nation, in both trade and investment," she will say.

Miller, who herself worked in advertising before becoming an MP, will refer to an advertising campaign that was launched overseas last year to promote Britain, known as the "Great" campaign. She will say: "You will all have seen the Great campaign which was launched last year… Heritage is Great … Creativity is Great … Innovation is Great. All these themes market Britain to the rest of the world as precisely what we are – great."

She will add: "British culture is perhaps the most powerful and most compelling product we have available to us. The most compelling platform upon which we can stand. The world was watching the UK during our Olympic and Paralympic year, and the world was reminded of just what Britain had to offer."

She will continue: "British culture and creativity are now more in demand than ever before … we should be increasingly proud to use the label 'made in Britain'. The world clearly thinks this is a commodity worth buying into."

When British arts are exported, they act, she will say, as a kind of "relationship marketing" exercise that helps "attract investment which will drive jobs and opportunities here at home. It opens doors for UK plc and makes it easier for businesses to export, and expand."